Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- app/controllers/settings/follower_domains_controller.rb
  Removed upstream. Did the same here. Maybe we should not have?
- config/locales/en.yml
  Upstream removed the “Authorized followers” page and associated
  translations. This is too close in the file to our glitch-soc-specific
  “flavour” string. No actual conflict.
- config/locales/ja.yml
  Same as above.
- config/locales/pl.yml
  Same as above.
- config/navigation.rb
  No real conflict. New route added too close to the glitch-soc-specific
  “flavours” one.
- config/webpack/configuration.js
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- config/webpack/loaders/babel.js
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
  The contents of this file have been moved to package.json.
- config/webpack/shared.js
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- config/webpacker.yml
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- jest.config.js
  The contents of this file have been moved to package.json.
- package.json
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- yarn.lock
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.

app/javascript/mastodon/features/ui/components/bundle.js

@@ -53,6 +53,11 @@ class Bundle extends React.PureComponent {
     const { fetchComponent, onFetch, onFetchSuccess, onFetchFail, renderDelay } = props || this.props;
     const cachedMod = Bundle.cache.get(fetchComponent);
 
+    if (fetchComponent === undefined) {
+      this.setState({ mod: null });
+      return Promise.resolve();
+    }
+
     onFetch();
 
     if (cachedMod) {